In a semiconductor device including a die pad as a mounting portion of a semiconductor chip, in which the semiconductor chip and the die pad are covered with a package material, it is important to discharge a Joule heat generated by a current flowing into the semiconductor chip efficiently to the outside of the semiconductor device.
As an approach for achieving a good heat radiation property, the die pad made of metal, serving as a heat radiating plate as well as a mounting portion, may be enlarged in a horizontal direction, to reduce the thermal resistance of the die pad. This approach, however, is disadvantageous in that it enlarges the size of the semiconductor device in the horizontal direction, making the die pad less compact.
As another approach for achieving a good heat radiation property, the die pad made of metal may be thickened to reduce the thermal resistance of the die pad. This approach, however, is not practical because micro fabrication of a thick metal plate is difficult.